Lantronix XPress-DR: Missing authentication enables configuration overwrite via UDP
Summary
Lantronix XPress-DR and XPress-DR-I industrial device servers up to firmware 8.1.0.0 accept configuration queries and writes on UDP port 30718 without authentication. A remote attacker can read the live configuration and overwrite the IP address and serial forwarding settings, and the changes persist across reboots. The product series is end-of-life since February 2025, and no fixed firmware is known. Exploitation requires network access to UDP port 30718.
Affected
- Lantronix XPress-DR firmware 8.1.0.0 and earlier
- Lantronix XPress-DR-I firmware 8.1.0.0 and earlier
Fixed in
Unknown. No fixed firmware version has been published, and the product series is end-of-life.
Workaround
- Block UDP port 30718 at firewalls or perimeter devices, or allow it only from trusted management hosts.
- Disable port 77FEh (30718) in the device Security settings (option 6, "Disable port 77FEh" set to Y) via Telnet or CLI, then save and exit.
Exploitation
- CISA SSVC: exploitation none, automatable yes, technical impact total.
- Not listed in CISA KEV.
- No public proof-of-concept found in research; this does not rule one out.
- EPSS 0.00618.
Our recommendation
- Inventory all XPress-DR and XPress-DR-I units and their firmware versions.
- Confirm that UDP port 30718 is not reachable from the internet, guest networks or other untrusted segments.
- Block UDP port 30718 except from specific management hosts, or disable the service if it is not needed.
- Plan replacement of the end-of-life devices, since no fix is known.
- Monitor the NVD and VulnCheck entries for a vendor advisory or fixed version.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- VulnCheck advisory www.vulncheck.com
- Lantronix end-of-life notice PCN-753 cdn.lantronix.com
- OpenCVE CVE-2026-109439 app.opencve.io
- VulDB entry 420240 vuldb.com
- Vulners CIRCL CVE-2026-109439 vulners.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 31 Oct 2026, 01:52.
Original description (NVD)
Lantronix XPress-DR and XPress-DR-I (CoBos-family) firmware through 8.1.0.0 contains a missing authentication vulnerability that allows remote attackers to read and persistently overwrite device configuration by sending crafted frames to the unauthenticated UDP configuration protocol on port 30718. Attackers can send a type 0xF8 query to read live configuration data and a type 0xFD frame with exactly 0x78 body bytes to rewrite the device IP address and serial-channel forwarding records, causing changes to commit to EEPROM and persist across reboots. The XPress-DR product series reached end-of-life/end-of-support in February 2025.
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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